Is it possible, or could it be possible to add an option to force a selected job to render ahead of the rest of the queue? (in Backburner it was the critical priority option that did it)

I seem to have to shuffle around job priorities if I want something to render ahead of the rest of the queue.

We will often have a few jobs at 100 that are highest priority, but If I have a quick test that needs rendering I will have to change those other jobs to a lower priority or suspend, at which point something else will usually start up rendering instead (and it gets a bit cat and mousey chasing them down)

I'd use pools for that. I want to say we named our "Crisis Friday" back in the day? That was used when the whole farm needed to be tasked with a particularly high priority job.

The idea is that Pools by default have a higher priority in the scheduler than the job priority value, and you can have pools apply to just a few machines. That means you could allocate a few really fast machines to pool "Testing" and whenever you need, just make sure your submitted job is sent to that pool instead of the default "none".